According to a July 2011 diagnostic discussion released by the Climate Prediction Center of the National Oceanic Atmospheric Administration (NOAA) and NOAA’s National Weather Service, “the possibility of a return to La Niña during the Northern Hemisphere fall 2011 has increased over the past month.”  David Stooksbury, Ph.D., Georgia’s state climatologist and associate professor of Engineering and Atmospheric Sciences at the University of Georgia, explained “La Niña patterns typically produce a dry, warm winter, which results in drought conditions during the following summer.”

“We need a wet winter to recover from this year’s drought, which was brought on by a La Niña pattern in the 2010 winter.  Right now, research out of NOAA indicates we may be in store for a double-dip La Niña,” Stooksbury said.

However, other forecast models indicate a “neutral” weather pattern for this winter, which typically leads to winters of variable temperatures and precipitation.  Atmospheric circulation conditions over the central Pacific Ocean, and sea surface and subsurface temperatures in the Pacific Ocean are key data inputs to seasonal climate outlooks for the southeastern United States.  These inputs are updated every week on the Climate Prediction Center website at El Niño/La Niña Current Conditions and Expert Discussions.

Breaking the drought

According to Stooksbury, major droughts are almost always the result of a dry winter.

“If we don’t get enough moisture from November to April, then we will typically be in drought conditions beginning May 1 and continuing until mid-August.  Once we’re in summer, we don’t have major rainfall events other than from a tropical storm,” he said.

November to April is the period when moisture is added to the soil in Georgia.  Evaporation is relatively low and plants are dormant.  As of April 15, the soil reaches a breakeven point when the amount of rainfall equals the amount of moisture lost through evaporation and plant use.

“By July, we’re losing a quarter to a third of an inch of moisture per day from the soil,” Stooksbury explained.   “With no moisture in the soil to evaporate, the sunlight all goes into heating the soil, which drives air temperatures higher.  That’s why droughts and high temperatures tend to play off each other.”

Mid-August is the time for the tropical storm season to pick up in the tropics.  This season is expected to be active, as tropical storm Don, this year’s fourth named storm, already made landfall in Texas.

“There is some hope there that we could get widespread heavy rains from a tropical system, but we have no ability to forecast who will be impacted.  And one storm will not break the back of the drought unless it’s of the magnitude of 1994’s remnant’s of tropical storm Alberto, which dropped 20 inches of rain on Georgia,” Stooksbury said.

Developing useful climate products

As the state climatologist, Stooksbury assists state agencies with their climate needs.  He works with the agricultural extension service, the marine extension service on coastal issues and helps with state emergency planning for hurricanes and other weather-related events.

Stooksbury is also on the executive committee for the Southeast Climate Consortium (SECC), a multidisciplinary, multi-institutional team that conducts research and outreach to a broad community of potential users and forms partnerships with extension and education organizations. Besides the University of Georgia, other institutional members of SECC include: Auburn University, Clemson University, Florida State University, North Carolina State University, University of Alabama-Huntsville, University of Florida and University of Miami.

A focus on outreach and partnerships helps ensure that the climate products developed by the SECC are useful.  Among their recent product developments is www.agroclimate.org, a web-based climate service that currently provides background climate information and tools, crop information and tools for peanuts, tomatoes and potatoes, forest management and wildfire risk assessment tools, and links to other relevant websites.

“Right now the SECC is talking to water resource managers to better understand how they use climate information.  The goal is to develop a useful website for this user group,” Stooksbury explained.

For more information, contact David Stooksbury at (706) 583-0156 or by email at stooks@engr.uga.edu.

Comments